Privacy concerns over DNA being used for crime investigations

As many of you are probably aware –– in April, 2018, a suspect in California’s notorious “Golden State Killer” cases was arrested, after decades of eluding the police [see attached article + editorial]. Using a novel forensic approach (using an online open-access genetic database, populated by individuals researching their family trees), investigators recognized the suspect by first identifying his relatives. Following this news announcement, media outlets expressed some privacy concerns about police access to personal genetic data generated by, or shared with, genealogy services.

Recent data from 1,587 survey respondents, however, provide preliminary reason to question whether such concerns are overstated. Still, limitations on police access –– to genetic genealogy databases, in particular –– may be desirable for reasons other than current public demand for them. Criminologists predict that it could soon be possible to search crime-scene DNA for links to nearly all Americans of European descent. Clearly, it won’t be long before other ethnic-descent data will similarly become available.

From the mid-1970s to the late 1980s –– a string of burglaries, sexual assaults, and murders in California by “the Golden State Killer” had remained unsolved, until April 2o18, when police arrested Joseph James DeAngelo; he was identified as a suspect, in large part, by matching crime-scene DNA to genetic profiles posted by his distant relatives on the genetic-genealogy website GEDmatch. This website allows people to upload data from consumer genetic companies, in order to search for relatives. In fact, in the 4 months since April, more than a dozen other crime cases have been solved, using this technique.

The method is known as “long-range familial search”. They analyzed anonymized DNA profiles from 1.28 million MyHeritage customers. Like similar firms, the company allows customers to search for relatives who share DNA inherited from a common ancestor. The researchers found that 60% of MyHeritage customers had a third cousin (or closer relative) in its database. Searches of 30 randomly selected GEDmatch profiles found a similar rate of relative matching.

Intriguingly, such databases can identify many more people who aren’t in the database. DeAngelo was not on GEDmatch; however, detectives found him, by using pro­files of his third cousins. It is now estimated that a database containing genetic profiles of 3 million Americans of European descent could enable identification of 90% of this demographic, using public genealogy records. GEDmatch is growing by 1,000–2,000 profiles each day, meaning that the database should reach 3 million in another few years. Wow.


PLoS Biol Oct 2o18; 16: e2006906 [article] & Nature 18 Oct 2o18; 562: 315–316 [editorial]

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